ATHEROMATOUS RENOVASCULAR DISEASE: OVERVIEW AND CHALLENGES

Prediction and assessment of responses to renal artery revascularization with dynamic contrast-enhanced magnetic resonance imaging: a pilot study

The aim of this study was to assess the potential of dynamic contrast-enhanced (DCE) MRI to predict and evaluate functional outcomes after renal artery revascularization for renal artery stenosis (RAS). The single-kidney glomerular filtration rate (SK-GFR) was measured in 15 patients with atherosclerotic RAS with DCE-MRI and radioisotopes at baseline and 4 mo after revascularization. DCE-MRI also produced measurements of blood flow, blood volume, extraction fraction, tubular transit time, and functional volume. Stented kidneys (n = 22) were divided into three response groups on the basis of the changes in radioisotope SK-GFR: improved (n = 5), stable (n = 13), and deteriorated (n = 4). A good agreement was found between SK-GFR values from DCE-MRI and radioisotopes (correlation coefficient: 0.91). Before intervention, kidneys that improved had lower extraction fraction, higher blood volume, longer tubular transit time, and lower SK-GFR. After intervention, improved kidneys had increased functional volume, and deteriorated kidneys had reduced functional volume and extraction fraction. Revascularization improved blood flow and blood volume in all groups. This pilot study led to the hypothesis that well-vascularized kidneys with reduced extraction fractions are most likely to benefit from revascularization. More generally, DCE-MRI has the potential to replace radioisotope measurement of SK-GFR and may improve patient management by providing additional information on tissue perfusion.

Optimal medical management in patients with renovascular hypertension

Renovascular hypertension refers to the rise of arterial pressure due to reduced perfusion of the kidney caused by the stenotic renal artery/ies. The most common cause of stenotic renal artery is atherosclerosis. Atherosclerotic renal stenosis is usually part of a systemic syndrome that involves hypertension, intrinsic renal damage, and cardiovascular morbidity. So far, large trials have not proven the superiority of interventional therapies to medical management. As a result, renal artery stenosis should be treated mainly as a coronary artery disease equivalent focusing on rigorous management of hypertension, hyperglycemia, and hyperlipidemia. Antihypertensive treatment should include renin-angiotensin system blockade medication in most cases, while HMG-CoA reductase inhibitors (statins) can be used even in chronic kidney disease with safety. Lifestyle modifications, such as cessation of smoking, and antiplatelet therapy have reduced the risk of cardiovascular events in high-risk patients.